A novel strategy to control and regulate infrared (IR) radiation using 2-dimensional nanosheets of a chemical called hexagonal boron nitride have potential for deployment as radiative heat barrier, thermal camouflage and in thermal management applications.
Infrared (IR) radiation with wavelength ranging from 780 nm to 1000 nm, present in solar radiation, sustains life on Earth. However, excess exposure to IR radiation, which constitutes about 50% of Sun’s radiation, can be undesirable from the viewpoints of both discomforting ambient temperature and possible health disorders. Effective control and management of IR radiation has attracted much attention for reducing the ever-increasing energy demands, such as, air-conditioning.
Scientists from the Centre for Nano and Soft Matter Sciences (CeNS), Bengaluru, an autonomous institute of Department of Science and Technology have come up with a novel strategy to control and regulate IR radiation. The method employs solution-processed 2-dimensional nanoflakes of hexagonal boron nitride (h-BN) developed by Dr. HSSR Matte and his student Priyabrata Sahoo, and preferentially assembling them in a polymer network liquid crystal.
The new concept could be a paradigm shift in this area as every single constituent of this multicomponent material is IR transparent, but their careful combination under specific conditions and preferential placement brings about a device that is extremely effective in IR regulation, explained Dr. Krishna Prasad and Dr. Shankar Rao who jointly supervised this research,.
This feature is demonstrated in several ways including scattering measurements, thermal imaging, passive radiative cooling, and reflectivity features, and is well supported by numerical simulations carried out by Dr. Sikdar at IIT Guwahati.
The system also has much higher mechanical strength as confirmed by nanoindentation studies. Gayathri Pishorady, a student and primary researcher in this work, foresees the strategy to offer a more generic way of developing IR regulators.
The work is published in a recent issue of Materials Horizons (Mater. Horiz., 11, 554 (2024); and a patent application has been filed.
Publication link : DOI: 10.1039/d3mh01467c
Top panel: Schematic diagram showing (a) PNLC and (b) PNLC-BN architecture with polymer fibres (maroon) and the h-BN flakes (cyan) in the midst of liquid crystal molecules (yellow).
Bottom panel: Thermal imaging and quantification of thermal regulation on exposure to hot surface with captured IR camera images. The image is much cooler for PNLC-BN device than PNLC device alone.
